PHP仿GD生成BMP图片

PHP仿GD生成BMP图片 function imagebmp(&$im, $filename = '', $bit = 8, $compression = 0){if (!in_array($bit, array(1, 4, 8, 16, 24, 32))){$bit = 8;}else if ($bit == 32) // todo:32 bit{$bit = 24;}$bits = pow(2, $bit);// 调整调色板imagetruecolortopalette($im, true, $bits);$width = imagesx($im);$height = imagesy($im);$colors_num = imagecolorstotal($im);if ($bit {// 颜色索引$rgb_quad = '';for ($i = 0; $i {$colors = imagecolorsforindex($im, $i);$rgb_quad .= chr($colors['blue']) . chr($colors['green']) . chr($colors['red']) . "\0";}// 位图数据$bmp_data = '';// 非压缩if ($compression == 0 || $bit {if (!in_array($bit, array(1, 4, 8))){$bit = 8;}$compression = 0;// 每行字节数必须为4的倍数，补齐。$extra = '';$padding = 4 - ceil($width / (8 / $bit)) % 4;if ($padding % 4 != 0){$extra = str_repeat("\0", $padding);}for ($j = $height - 1; $j >= 0; $j --){$i = 0;while ($i {$bin = 0;$limit = $width - $i for ($k = 8 - $bit; $k >= $limit; $k -= $bit){$index = imagecolorat($im, $i, $j);$bin |= $index $i ++;}$bmp_data .= chr($bin);}$bmp_data .= $extra;}}// RLE8 压缩else if ($compression == 1 && $bit == 8){for ($j = $height - 1; $j >= 0; $j --){$last_index = "\0";$same_num = 0;for ($i = 0; $i {$index = imagecolorat($im, $i, $j);if ($index !== $last_index || $same_num > 255){if ($same_num != 0){$bmp_data .= chr($same_num) . chr($last_index);}$last_index = $index;$same_num = 1;}else{$same_num ++;}}$bmp_data .= "\0\0";}$bmp_data .= "\0\1";}$size_quad = strlen($rgb_quad);$size_data = strlen($bmp_data);}else{// 每行字节数必须为4的倍数，补齐。$extra = '';$padding = 4 - ($width * ($bit / 8)) % 4;if ($padding % 4 != 0){$extra = str_repeat("\0", $padding);}// 位图数据$bmp_data = '';for ($j = $height - 1; $j >= 0; $j --){for ($i = 0; $i {$index = imagecolorat($im, $i, $j);$colors = imagecolorsforindex($im, $index);if ($bit == 16){$bin = 0 $bin |= ($colors['red'] >> 3) $bin |= ($colors['green'] >> 3) $bin |= $colors['blue'] >> 3;$bmp_data .= pack("v", $bin);}else{$bmp_data .= pack("c*", $colors['blue'], $colors['green'], $colors['red']);}// todo: 32bit;}$bmp_data .= $extra;}$size_quad = 0;$size_data = strlen($bmp_data);$colors_num = 0;}// 位图文件头$file_header = "BM" . pack("V3", 54 + $size_quad + $size_data, 0, 54 + $size_quad);// 位图信息头$info_header = pack("V3v2V*", 0x28, $width, $height, 1, $bit, $compression, $size_data, 0, 0, $colors_num, 0);// 写入文件if ($filename != ''){$fp = fopen($filename, "wb");fwrite($fp, $file_header);fwrite($fp, $info_header);fwrite($fp, $rgb_quad);fwrite($fp, $bmp_data);fclose($fp);return true;}// 浏览器输出header("Content-Type: image/bmp");echo $file_header . $info_header;echo $rgb_quad;echo $bmp_data;return true;}复制代码